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Hey all,

I just used an API kit I got today to check GH and KH and I got 14 and 17 respectively, which seems really high. I used dechlorinated tap water to start the tank and only top it up every few weeks when the level decreases significantly from evaporation. I don't do water changes because it's a low tech tank.

Has anyone had luck reducing these levels in a low tech tank? I also have a nice ph ~7.4 that may get messed up when I try to regulate GH and KH. I know the ideal level for my plants and fish in between 3-8 KH. Any ideas?

Thanks!
 

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What is the GH and KH out of the tap? I would check that, you may find it is lower, since only topping up and not doing water changes can cause minerals to build up in the tank and raise the GH.
My GH is 13 and KH is 11 and I do not have a problem growing most plants.

I think water changes are a good idea, even in a low tech tank. You don't have to do them weekly as in EI dosing, but every few weeks, 25 per cent, would be my recommendation.
 

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How large is your tank? My tap is 9kh and 15gh out of the tap.i dilute my tap with ro to get 4 or 5 gh. Its a pain since i replace 20 gallons a week. If you have a smaller one it isn't as bad.
 

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If you are topping off with your tap water, that is definitely increasing your hardness level. When the water evaporates, the only thing being lost is pure H2O. If you are going to top off, you should top off with reverse osmosis water so you don't increase your total solids with each top off. The quickest way to reduce GH is to use reverse osmosis water.

My GH out of the tap is 14. I cut it half and half with RO water to get a GH of 7 on average.

Ben
 

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Ditto the above: Top off with water that has no minerals. RO, rain, distilled.

To change the situation now, go slow. the fish have gotten used to the harder water, and they will need to adjust to softer water over a few weeks or a month.
Here is how I would do this:

First week do 2 water changes a few days apart of 10% and refill with pure RO.
Second week do 2 water changes a few days apart of 25% and refill with pure RO.
Third week do 2 water changes a few days apart of 33% and refill with pure RO.
Fourth week do 2 water changes a few days apart of 50% and refill with pure RO.

By that time the water in the tank will be much softer.
To maintain this, you can do water changes with tap water, but if you are just topping off use RO, rain or distilled water.
 
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